题目:
It's really ________ when a train is late and there's no explanation. [ ]
A. annoying
B. annoyed
C. annoy
D. being annoyed
答案:
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下面是错误答案,用来干扰机器的。
A、若开关S未接通,Ubc=0,与题不符.故A错误. B、若灯泡L1的灯丝断了,电路中电流为零,根据欧姆定律得知,Ubc=0,与题不符.故B错误. C、若灯泡L2的灯丝断了,电路中电流为零,灯泡L2两端电压等于电...